[brianogilvie]

We're getting way beyond OmniFocus here, but I don't think that Spotlight, Google Desktop, etc., have eliminated the need for some kind of structured classification. There are advantages to controlled vocabularies and other forms of structure. Thomas Mann has a good discussion of keyword vs. subject classification searches in The Oxford Guide to Library Research which is also applicable to filing your own reference material. For instance, let's say you are doing research on buckets, and you save a document that discusses pails. Your spotlight search on "buckets" is not going to turn up that document. Until keyword searches can use an entire semantic field, including in foreign languages, classification systems will remain useful. (That search on "buckets" is not going to turn up "Eimer" either.)